To briefly illustrate some of the points to be brought out, let us consider the plan of the shop shown in Fig. 186, and its sectional elevation shown in Fig. 187.
The outer walls should be filled in with some good weather-resisting material, of which there is nothing better than brick. These walls should be of good height and have a sufficient window area to supply light well in toward the middle of the shop.
The method of heating and ventilating best adapted for a foundry is the indirect fan system. One or more large fans, situated generally toward the ends of the shop, draw fresh air in through a compact system of steam coils, and, by means of overhead piping, deliver it to all portions of the shop. The impure gases are carried off through ventilators in the clearstory at the top of the roof.
Fig. 186. Typical Plan of Foundry.
The floor of the foundry should consist of molding sand, the depth of the sand floor varying with the class of work to be done. If the natural soil of the grounds is open and porous, a thickness of 3 or 4 inches of clay, well rolled down, should be put in underneath the sand floor. This will help greatly in keeping the molding floor in good condition, as it prevents the moisture draining out of the sand.
The foundry office should be located at such a point that the foreman can command a view of the whole shop. It should be convenient to the different departments and at the same time be protected as far as possible from dust. The office room, shown in Fig. 186 at A, is built on the outside of the main building, but has a large bay window which projects a few feet into the shop from which all corners of the foundry can be seen.
A space B, having suitable low tables and shelving, is reserved near the office for the temporary storing of patterns in daily use. This brings them directly under the attention of the foreman and his assistants who can readily check the patterns as they come in and quickly find those requiring prompt attention.
Fig. 187. Typical Elevation of Foundry.
At C are shown the cupolas, directly opposite the foreman's office, and so situated that all of the molding floors may be served as quickly as possible without interfering one with the other.
In large foundries there are two or more cupolas, to admit of different mixtures being melted simultaneously. Often a comparatively small cupola is installed near the floor for light work for the service of that floor alone.
The blowers should be placed near the cupolas, avoiding long connecting wind pipes. The application of electric motors removes the necessity of concentrating the power at one point in the shop.
The main bay of the foundry is devoted to the heaviest work and is served by at least two overhead cranes.
The heavy green-sand castings are made at one end so that the flasks for this work may be stored in yards near by and be brought in through the door D. These molds are made up farthest from the cleaning shed, because only the castings themselves need be transferred there.
The flasks and rigging for the dry-sand and loam molds should be brought in through the opposite door E. The loam work, as a rule, is the most bulky to handle and should be nearest the cleaning sheds so that it need not be carried across the other floors. Both dry-sand and loam floors are convenient to the large ovens F.
The core shop is situated in the side bay at G, to make it convenient to swing the large cores on to the buggies to be run into the large ovens. A jib crane near the corner of these ovens makes the men working on such cores independent of the traveling crane. The ovens for small cores are built along the side of the large ovens and utilize the same stoke hole, ash pit, and stack.
Distributed through the side bays also are the medium-work floor //, the light-work floor /, and the molding-machine floor J, This ensures a supply of good light necessary to the smaller details of this class of work.
The molding machines are placed on that side of the shop near the sand storage sheds, to allow for handling the sand by means of belt conveyors with hoppers above the machines, an illustration of which is shown in Fig. 188.
The sand-mixing space is in the side bay near the cupolas at K, and is furnished with power from independent motors or from a jack shaft leading from the blower room. This position affords direct access to the sand bins. The raw material after being mixed and tempered is delivered by barrow or sand car direct to the Various floors. The mixers might be installed in one of the storage vaults across the roadway.
The quickest means of unloading either wagon or carload lots of material is by dumping, where the material can be so handled. One of two things is necessary to accomplish this: either the storage bins must be placed in a basement underneath the roadbed; or the roadway must be run up an incline over the top of the bins. The former method is more frequently met with in the crowded condition of the large cities, but the latter is preferable because less time is consumed in running material up an incline in large quantities than is required to hoist small quantities more frequently from a basement.
At L and L, Figs. 186 and 187, are shown the storage yards for pig iron and coke; these are on a level with the charging platform of the cupola, C and C, and the materials can be loaded on cars and pushed directly to the charging door. In some modern shops these push cars are built so that their load may be dumped as a whole into the cupola.
The storage for core-oven fuel, sands, and clay, is shown at MM, in bins built underneath the tracks and on a level with the foundry floor. These bins should be arranged to open on top, with a chute under the track and a trap at the side, so that coal or sand may either be dumped or shoveled directly into them.
In the largest shops a standard-gage track should run directly through the main foundry, and there should be also similar tracks through the roadway next the cupola bay for convenience in removing the dump. The track over the storage bins has been mentioned.
Two methods of transferring material between departments within the shop, aside from the cranes, are the overhead-trolley system, Fig. 189, and the narrow-gage industrial railway. The former is of advantage in manufacturing plants where the loads to be transferred are nearly uniform in weight and frequency of handling. This system leaves gangways smooth and free from obstructions. For general work, however, the industrial railways are more frequently installed. These serve all floors to deliver flasks, sand, or iron, and to remove castings.
Of the many styles of overhead traveling cranes that are on the market, those using electricity as the motive power are undoubtedly the most serviceable. The cranes in the main foundry indicated at 0', Fig. 187, should have two hoisting drums on the carriage; one for such light work as handling flasks, rigging, and patterns; the other for the heavy work on the large ladles and castings.
Small jib cranes furnished with a 2- to 4-ton air or electric hoist placed on the side of a man's floor make it possible for the molder and helper to handle work of considerable size by themselves, and prevent loss of time from waiting for the overhead crane.
The method of distributing the melted metal varies with the class of work made. In shops doing general jobbing work, the ladles for pouring the largest work are carried from the cupola directly by the overhead cranes.
For serving the floors in the bays one of the systems mentioned above is generally used. The metal is conveyed to the floor in a large ladle and from this smaller ones are filled and carried by hand or by a small crane to the molds.
The cleaning department should be situated at one end of the shop near E, Fig. 186, or in a shed extension to the foundry proper. It requires space to pile the castings as they are brought from the floors with sufficient room for the men to begin work on these piles. As a rule, the smaller castings are first collected and put through the tumbling barrels, then the medium work is cleaned by hand or by sand blast; this leaves room for work around the largest pieces. As soon as castings are cleaned they are weighed and shipped to the customer, store house, or to the department which does the next operation upon them.